Telecommunications systems include sophisticated electronic switching equipment which is able to provide extensive data on the state and performance of the equipment and other aspects of a telecommunications system. Mobile telecommunications systems, in particular, are subjected to a wide variety of operating conditions which depend to a substantial extent on the movement and use of mobile telecommunications stations. The operating conditions of a mobile system include an unpredictable element and can give rise to a variety of different faults which need to be detected. The equipment of mobile telecommunications systems and, in particular, the base stations used in the systems, generate a considerable amount of data from which faults can be determined. It would be advantageous to be able to monitor a telecommunications network by accessing data which may be pertinent to fault determination and then analyse that data to detect faults.